“Hayes Alba Warren 12/31/17 Best gift to ring in the New Year!!” the "Fantastic Four" actress posted on Instagram Monday, along with a photo of the newborn.
“Cash and I feel so blessed. Haven and Honor are already obsessed with their new baby bro," she added, along with the hashtag, "#familyof5.”
Warren took to Instagram as well, captioning a photo of him holding his son, “Hayes Alba Warren: You sure know how to ring in the new year! You showed up a few days early but we couldn’t be any happier.”
“Your Mamma is the strongest woman I know … you’re so lucky to have her by your side,” he continued. “You have two amazing sisters who already adore you and I know you’ll be thankful to have them guide the way.”
Alba, 36, and Cash, 38, were married in 2008. That same year they welcomed their eldest, daughter Honor. Their other little girl, Haven, is six.